1. Field of the Invention
This invention relates to an audio signal encoding apparatus. This invention also relates to an optical recording medium. In addition, this invention relates to an audio signal decoding apparatus. Furthermore, this invention relates to a method of transmitting an audio signal.
2. Description of the Related Art
Highly efficient encoding of an audio signal includes a step of compressing the audio signal. Highly efficient encoding techniques are classified into two types; the lossy encoding techniques and the lossless encoding techniques. Among the lossy encoding techniques, the xe2x80x9cacoustic encodingxe2x80x9d is well known as a technique which renders the data deterioration acoustically undetectable. On the other hand, according to the lossless encoding and decoding techniques, the recovered data are exactly the same as the original data.
In general, a sampled or uniformly quantized audio signal has significant redundancy. During the encoding of such an audio signal, the degree of the compression of the audio signal rises as redundancy is more effectively removed therefrom.
It is a first object of this invention to provide an audio signal encoding apparatus having a higher compression performance.
It is a second object of this invention to provide an improved optical recording medium.
It is a third object of this invention to provide an improved audio signal decoding apparatus.
It is a fourth object of this invention to provide an improved method of transmitting an audio signal.
A first aspect of this invention provides an audio signal encoding apparatus comprising means for adding a first audio signal and a second audio signal into an addition-result signal; means for subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; means responsive to the addition-result signal for generating a first difference signal representing a difference in the addition-result signal; means responsive to the subtraction-result signal for generating a second difference signal representing a difference in the subtraction-result signal; a plurality of first predictors having different prediction characteristics respectively and being responsive to the first difference signal for generating first different prediction signals for the first difference signal, respectively; a plurality of first subtracters for generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; means for selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; a plurality of second predictors having different prediction characteristics respectively and being responsive to the second difference signal for generating second different prediction signals for the second difference signal, respectively; a plurality of second subtracters for generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; and means for selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals.
A second aspect of this invention is based on the first aspect thereof, and provides an audio signal encoding apparatus further comprising means for generating a variable-rate bit stream in response to the first minimum prediction-error signal and the second minimum prediction-error signal.
A third aspect of this invention provides an audio signal decoding apparatus for processing a first minimum prediction-error signal and a second minimum prediction-error signal which are generated by an audio signal encoding apparatus comprising means for adding a first audio signal and a second audio signal into an addition-result signal; means for subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; means responsive to the addition-result signal for generating a first difference signal representing a difference in the addition-result signal; means responsive to the subtraction-result signal for generating a second difference signal representing a difference in the subtraction-result signal; a plurality of first predictors having different prediction characteristics respectively and being responsive to the first difference signal for generating first different prediction signals for the first difference signal, respectively; a plurality of first subtracters for generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; means for selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; a plurality of second predictors having different prediction characteristics respectively and being responsive to the second difference signal for generating second different prediction signals for the second difference signal, respectively; a plurality of second subtracters for generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; and means for selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals. The audio signal decoding apparatus comprises means for recovering the addition-result signal from the first minimum prediction-error signal; means for recovering the subtraction-result signal from the second minimum prediction-error signal; and means for recovering the first audio signal and the second audio signal from the recovered addition-result signal and the recovered subtraction-result signal.
A fourth aspect of this invention provides a method comprising the steps of adding a first audio signal and a second audio signal into an addition-result signal; subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; generating a first difference signal representing a difference in the addition-result signal; generating a second difference signal representing a difference in the subtraction-result signal; generating first different prediction signals for the first difference signal, respectively; generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; generating second different prediction signals for the second difference signal, respectively; generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals; and transmitting the first minimum prediction-error signal and the second minimum prediction-error signal to a communication line.
A fifth aspect of this invention provides an optical recording medium storing formatted information of a first minimum prediction-error signal and a second minimum prediction-error signal which are generated by an audio signal encoding apparatus comprising means for adding a first audio signal and a second audio signal into an addition-result signal; means for subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; means responsive to the addition-result signal for generating a first difference signal representing a difference in the addition-result signal; means responsive to the subtraction-result signal for generating a second difference signal representing a difference in the subtraction-result signal; a plurality of first predictors having different prediction characteristics respectively and being responsive to the first difference signal for generating first different prediction signals for the first difference signal, respectively; a plurality of first subtracters for generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; means for selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; a plurality of second predictors having different prediction characteristics respectively and being responsive to the second difference signal for generating second different prediction signals for the second difference signal, respectively; a plurality of second subtracters for generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; and means for selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals.
A sixth aspect of this invention provides a method of network-based transmission which comprises the steps of adding a first audio signal and a second audio signal into an addition-result signal; subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; generating a first difference signal representing a difference in the addition-result signal; generating a second difference signal representing a difference in the subtraction-result signal; generating first different prediction signals for the first difference signal, respectively; generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; generating second different prediction signals for the second difference signal, respectively; generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals; and transmitting the first minimum prediction-error signal and the second minimum prediction-error signal to a communication line.
A seventh aspect of this invention provides an audio signal encoding apparatus comprising means for selecting a first audio signal and a second audio signal from among signals composing a multi-channel audio signal; means for adding the first audio signal and the second audio signal into an addition-result signal; means for subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; means responsive to the addition-result signal for generating a first difference signal representing a difference in the addition-result signal; means responsive to the subtraction-result signal for generating a second difference signal representing a difference in the subtraction-result signal; a plurality of first predictors having different prediction characteristics respectively and being responsive to the first difference signal for generating first different prediction signals for the first difference signal, respectively; a plurality of first subtracters for generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; means for selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; a plurality of second predictors having different prediction characteristics respectively and being responsive to the second difference signal for generating second different prediction signals for the second difference signal, respectively; a plurality of second subtracters for generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; and means for selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals.
An eighth aspect of this invention is based on the seventh aspect thereof, and provides an audio signal encoding apparatus further comprising means for generating a variable-rate bit stream in response to the first minimum prediction-error signal and the second minimum prediction-error signal.
A ninth aspect of this invention provides an audio signal decoding apparatus for processing a first minimum prediction-error signal and a second minimum prediction-error signal which are generated by an audio signal encoding apparatus comprising means for selecting a first audio signal and a second audio signal from among signals composing a multi-channel audio signal; means for adding the first audio signal and the second audio signal into an addition-result signal; means for subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; means responsive to the addition-result signal for generating a first difference signal representing a difference in the addition-result signal; means responsive to the subtraction-result signal for generating a second difference signal representing a difference in the subtraction-result signal; a plurality of first predictors having different prediction characteristics respectively and being responsive to the first difference signal for generating first different prediction signals for the first difference signal, respectively; a plurality of first subtracters for generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; means for selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; a plurality of second predictors having different prediction characteristics respectively and being responsive to the second difference signal for generating second different prediction signals for the second difference signal, respectively; a plurality of second subtracters for generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; and means for selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals. The audio signal decoding apparatus comprises means for recovering the addition-result signal from the first minimum prediction-error signal; means for recovering the subtraction-result signal from the second minimum prediction-error signal; and means for recovering the first audio signal and the second audio signal from the recovered addition-result signal and the recovered subtraction-result signal.
A tenth aspect of this invention provides a method comprising the steps of selecting a first audio signal and a second audio signal from among signals composing a multi-channel audio signal; adding the first audio signal and the second audio signal into an addition-result signal; subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; generating a first difference signal representing a difference in the addition-result signal; generating a second difference signal representing a difference in the subtraction-result signal; generating first different prediction signals for the first difference signal, respectively; generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; generating second different prediction signals for the second difference signal, respectively; generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals; and transmitting the first minimum prediction-error signal and the second minimum prediction-error signal to a communication line.
An eleventh aspect of this invention provides an optical recording medium storing formatted information of a first minimum prediction-error signal and a second minimum prediction-error signal which are generated by an audio signal encoding apparatus comprising means for selecting a first audio signal and a second audio signal from among signals composing a multi-channel audio signal; means for adding the first audio signal and the second audio signal into an addition-result signal; means for subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; means responsive to the addition-result signal for generating a first difference signal representing a difference in the addition-result signal; means responsive to the subtraction-result signal for generating a second difference signal representing a difference in the subtraction-result signal; a plurality of first predictors having different prediction characteristics respectively and being responsive to the first difference signal for generating first different prediction signals for the first difference signal, respectively; a plurality of first subtracters for generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; means for selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; a plurality of second predictors having different prediction characteristics respectively and being responsive to the second difference signal for generating second different prediction signals for the second difference signal, respectively; a plurality of second subtracters for generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; and means for selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals.
A twelfth aspect of this invention provides a method of network-based transmission which comprises the steps of selecting a first audio signal and a second audio signal from among signals composing a multi-channel audio signal; adding the first audio signal and the second audio signal into an addition-result signal; subtracting the first audio signal from the second audio signal, and generating a subtraction-result signal; generating a first difference signal representing a difference in the addition-result signal; generating a second difference signal representing a difference in the subtraction-result signal; generating first different prediction signals for the first difference signal, respectively; generating first prediction-error signals representing differences between the first difference signal and the first different prediction signals, respectively; selecting a first minimum prediction-error signal representative of a smallest difference from among the first prediction-error signals; generating second different prediction signals for the second difference signal, respectively; generating second prediction-error signals representing differences between the second difference signal and the second different prediction signals, respectively; selecting a second minimum prediction-error signal representative of a smallest difference from among the second prediction-error signals; and transmitting the first minimum prediction-error signal and the second minimum prediction-error signal to a communication line.